High School On a basic level why aren't loops ##\equiv## strings?

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The discussion centers on the conceptual relationship between loops and strings in theoretical physics, suggesting that both can be viewed as fundamental building blocks, with loops representing closed strings and open strings as modified loops. However, significant differences exist, particularly regarding their underlying mathematical frameworks; loop quantum gravity deals with discrete units of space-time, while string theory operates within a continuous 10-11 dimensional framework. The conversation touches on the challenges of unifying these theories, acknowledging the complexities of their differing properties and equations. Some participants argue against equating loops with strings due to these fundamental distinctions. Ultimately, the discussion concludes that the question posed has been sufficiently addressed.
billtodd
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As far as I can tell (if we look at pictures, without equations), a loop can be considered as a 1-dimensional closed string; and an open 1-dim string can be considered as a loop that we cut one point on its boundary?

So basically the fundamental building block is the same whether you call it loop or string?


I prefer points though... :oldbiggrin:

Obviously there's also the background dependency and independency that conflicts between both of them; But if one were to unite between the two theories, I guess one should find a someway to complement between them.
How to do it exactly is yet beyond me as well, if it's even possible.
 
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Loop quantum gravity is about discrete units of space-time.

In string theory, strings are particles that existing within a 10-11 dimensional space-time that is continuous, rather than discrete, and often represented by branes or manifolds.
 
ohwilleke said:
Loop quantum gravity is about discrete units of space-time.

In string theory, strings are particles that existing within a 10-11 dimensional space-time that is continuous, rather than discrete, and often represented by branes or manifolds.
Isn't it the other way around? I.e. particles are strings. I assume there are strings that are not necessarily particles. There's also this theory called string field theory, which I know nothing about it.
 
billtodd said:
a loop can be considered as a 1-dimensional closed string
No it cannot, they are described by totally different equations.
That's like saying that electron can be considered as a photon, because both are zero-dimensional.
 
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The OP question is sufficiently answered (particularly in view of the kind of reference given). Thread closed.
 
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"Supernovae evidence for foundational change to cosmological models" https://arxiv.org/pdf/2412.15143 The paper claims: We compare the standard homogeneous cosmological model, i.e., spatially flat ΛCDM, and the timescape cosmology which invokes backreaction of inhomogeneities. Timescape, while statistically homogeneous and isotropic, departs from average Friedmann-Lemaître-Robertson-Walker evolution, and replaces dark energy by kinetic gravitational energy and its gradients, in explaining...

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